Nerve contact with muscle component in neuromuscular hamartoma

Neuromuscular hamartoma is a very rare soft tissue tumor; of which only 20 cases have been reported previously. None of these reports has described th e relation between. hamartomatous skeletal muscle and ne,ve fibers in the t umor. We experienced a patient with neuromuscular hamartoma arising at the brachial plexus. In this tumor, the localization of synaptophysin (SYP), S- 100 protein (SP), neuron-specific enolase (NSE) neurofilament protein (NFP) and myoglobin (MG) was immunohistochemically detected. The results showed that SYP and MG were diffusely localized in the hamartomatous muscle fibers , SP in the schwann cells, and NSE and NFP in the axons of the hamartomatou s nerve. Therefore, it is suggested that in the neuromuscular hamartoma, th e structure of the neuromuscular junction may be similar to that in the mot or endplate of the normal muscle, but it may not be functional, because the hamartomatous muscles could not contract by nerve stimulation.